Catheter having a force sensing distal tip

Abstract

A mapping and ablation catheter with contact force sensing capabilities at a distal end, includes a catheter body, a deflectable section, and a tip distal section which has a tip electrode and a contact force sensor for sensing a 3D contact force vector applied to the tip electrode. In contact with the tip electrode, the contact force sensor has a body and has at least one sensor with an electrical characteristic that is responsive to deformation of the body resulting from force vector. The sensor is adapted to receive an electrical current and to output an electrical signal indicative of a change in the electrical characteristic. In one embodiment, the sensor is a strain gage responsive to tension and compression of at least a portion of the body of the force sensor and the electrical characteristic of the strain gage that is monitored is electrical resistivity. In another embodiment, the sensor is responsive to strain and stress of at least a portion of the body, and the electrical characteristic being monitored is inductance or hysteresis loss.

Description

FIELD OF INVENTION[0001]The present invention relates to an electrophysiologic catheter useful for ablation and sensing electrical activity of heart tissue, in particular, an electrophysiologic catheter with contact force sensing capabilities at its distal end.BACKGROUND OF INVENTION[0002]Cardiac arrythmias, and atrial fibrillation in particular, persist as common and dangerous medical ailments, especially in the aging population. In patients with normal sinus rhythm, the heart, which is comprised of atrial, ventricular, and excitatory conduction tissue, is electrically excited to beat in a synchronous, patterned fashion. In patients with cardiac arrythmias, abnormal regions of cardiac tissue do not follow the synchronous beating cycle associated with normally conductive tissue as in patients with normal sinus rhythm. Instead, the abnormal regions of cardiac tissue aberrantly conduct to adjacent tissue, thereby disrupting the cardiac cycle into an asynchronous cardiac rhythm. Such a...

AI Technical Summary

Benefits of technology

[0009]In a more detailed embodiment, the catheter of the present invention includes a catheter body, a deflectable intermediate section and a tip section with a tip electrode and a contact force sensor susceptible to material strains produced by bending moments and both tension and compression forces applied to the catheter tip electrode. The contact force sensor has a cup shaped body, a plurality of radial spokes, an axial beam member, and at least one strain gage mounted on one of the spokes. The spokes converge at a centered hub on the body from which the beam member extends and is connected to the tip electrode so that an applied contact force vector is transmitted from the tip electrode to the beam member which deforms and strains the body of the force sensor. A gap is provided along the longitudinal axis between the tip electrode and body of the force sensor so that a moment load can be imported to the beam from a force vector acting on the tip electrode. Each spoke of the force sensor may have more than one strain gage mounted thereon, for example, two strain gages on opposite surfaces of the spoke mounted in symmetry of each other. In this symmetrical configuration, each strain gage cancels the other's temperature effects when a half bridge electrical configuration is used for strain measurement and it also increases and doubles the change in the resistance output (resistance measurement sensitivity) per unit strain input to the body.

Problems solved by technology

Cardiac arrythmias, and atrial fibrillation in particular, persist as common and dangerous medical ailments, especially in the aging population.

This is a potentially life-threatening arrhythmia because it may lead to ventricular fibrillation and sudden death.

However, proper positioning of the tip electrode relative to tissue wall is not always possible.

Images